CN112161866A - Potentiometer control dynamic tracking bidirectional synchronous displacement measuring device - Google Patents
Potentiometer control dynamic tracking bidirectional synchronous displacement measuring device Download PDFInfo
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- CN112161866A CN112161866A CN202010984773.3A CN202010984773A CN112161866A CN 112161866 A CN112161866 A CN 112161866A CN 202010984773 A CN202010984773 A CN 202010984773A CN 112161866 A CN112161866 A CN 112161866A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0019—Compressive
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/025—Geometry of the test
- G01N2203/0256—Triaxial, i.e. the forces being applied along three normal axes of the specimen
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Abstract
The invention provides a potentiometer control dynamic tracking bidirectional synchronous displacement measuring device, and belongs to the technical field of geotechnical tests. The device comprises a stepping motor, an electric sliding table, a laser displacement sensor, a separated rotatable fixture, an electric sliding table top, a local displacement sensor, a potentiometer control structure and an electric sliding table base. The stepping motor connecting shaft is connected with the head end of the transmission shaft of the electric sliding table; the laser displacement sensor is connected with the separated rotatable fixture, and the stroke assembly of the laser displacement sensor and the separated rotatable fixture is assembled at the central position of the upper end of the table top of the electric sliding table; assembling a local displacement sensor and a potentiometer control structure at the center of the lower end of the table top of the electric sliding table; the lower end of the electric sliding table is embedded into the electric sliding table base and is leveled and fixed. The invention can realize the accurate measurement of the axial-radial displacement of different local measuring points of the triaxial sample, can be used for static force and dynamic force tests, and is not restricted by loading conditions; the method has the advantages of simple installation method, simple and convenient operation, high measurement precision and good popularization value.
Description
Technical Field
The invention belongs to the technical field of geotechnical tests, and relates to a potentiometer-controlled dynamic tracking bidirectional synchronous displacement measuring device, in particular to a device for dynamically tracking and synchronously measuring local axial-radial displacement of a triaxial sample.
Technical Field
In the conventional triaxial test process, the upper end part and the lower end part of a triaxial test sample are respectively contacted with a test sample cap and a test sample base, and due to the constraint of friction force, in the test loading process, the stress conditions of the end part of the test sample are different from the stress conditions of the middle section of the test sample, and the obvious difference can occur under the conditions of different densities, confining pressures or loading rates and the like. Due to the influence of the stress condition, the development of each local strain of the sample is extremely uneven.
At present, in order to better measure the strain development of a triaxial sample accurately, a large number of scholars propose relatively feasible methods, mainly including the following methods:
(1) fixed local displacement sensor measuring method
The method mainly comprises the steps that a local displacement sensor is arranged on the outer surface of a triaxial sample to carry out point position measurement, but the method can only measure local radial deformation; except for this, the similar method is to install the local displacement sensor inside the pressure chamber and fix it on the pressure chamber upper disk or pillar, the contact of the local displacement sensor can not move with the change of the position of the measuring point, and the measuring result is inaccurate.
(2) Hall effect sensor measurement
The method is that a Hall effect sensor is arranged on a yoke at one end of a hinge which is fixed on the surface of a triaxial sample, when the sample is deformed, a transducer of the yoke is opened or closed, and the yoke at the other end of the hinge is rotated. Thus, there is a relationship between the hall effect sensor readings and the radial deformation of the sample, thereby measuring the radial deformation of the three-axis sample. The method has the advantages that the equipment installation difficulty is extremely high, the fixed sheath can pierce the latex film, the test is not facilitated, and only the radial deformation of the triaxial sample can be measured.
(3) Near object sensor measurement
The method has the main principle that: when eddy currents circulate in the metal target, the magnetic field will be lost. The loss of magnetic field varies with the distance between the probe and the three-axis sample surface measurement point. The coils in the transducer induce eddy currents in the target that vary with the distance between the transducer and the three-axis sample surface measurement points. Changes in eddy currents cause corresponding changes in impedance, which can be measured by connecting the sensor to a Wheatstone bridge circuit. The method mainly comprises a fixed type and a floating type, and although the measurement precision is relatively high and reaches 0.001%, the sensor is very high in price and very difficult to install. This method is currently used only to measure axial deformation of a specimen.
(4) Fiber Bragg grating linear deformation sensor measuring method
The method is a measuring method combining a fiber Bragg grating linear deformation sensor based on an optical fiber technology with a traditional LDT sensor, and the sensors are all arranged on the surface of a sample. The basic principle of the method is similar to that of the LDT sensor, and is not described in detail. The precision of the method mainly depends on the resolution and the calibration coefficient of the fiber Bragg grating linear deformation sensor. Since this method uses a large amount of adhesive during installation, creep errors of the adhesive will result in the accuracy of the measurement not being guaranteed. This method is only used to measure the axial deformation of the sample.
(5) Image visual tracking measuring method
The method mainly comprises the steps of adopting an industrial camera to track and shoot a sample in a loading process in real time, processing the sample by using an image analysis program according to a real-time image, and obtaining the deformation condition of the sample. The method can simultaneously measure the axial deformation and the radial deformation of the sample.
Therefore, a measuring device capable of synchronously measuring local axial-radial deformation of a triaxial sample is needed.
Disclosure of Invention
The invention aims to provide a device which is simple in equipment and convenient to test and operate, can reduce the interference on a sample in the test process, and can accurately measure the local axial-radial displacement of a triaxial sample, so that the problem of local deformation measurement of the sample and the problem of local large deformation measurement of the sample in the loading process are solved.
In order to achieve the purpose, the invention adopts the technical scheme that:
a potentiometer control dynamic tracking bidirectional synchronous displacement measuring device can dynamically track and synchronously measure local axial-radial displacement of a triaxial sample and is used for measuring the local axial-radial displacement of the sample in a conventional static and dynamic triaxial test. The measuring device mainly comprises a stepping motor 100, an electric sliding table 200, a laser displacement sensor 300, a separated rotatable fixture 400, an electric sliding table top 500, a local displacement sensor and potentiometer control structure 600 and an electric sliding table base 700. Laser displacement sensor 300 through the bolt with the combination assembly that the disconnect-type rotatable anchor clamps 400 are connected and are formed and put the department in the upper end central point of electronic slip table mesa 500a side, this side lower extreme central point department of electronic slip table mesa 500 assembles local displacement sensor and potentiometre control structure 600, electronic slip table mesa 500 another side is connected with electronic slip table 200, and the long axis of electronic slip table mesa 500 is parallel with electronic slip table 200 major axis. The head end of a transmission shaft of the electric sliding table 200 is connected with a connecting shaft of the stepping motor 100, and the tail end of the electric sliding table 200 is embedded into the electric sliding table base 700 and is leveled and fixed.
The local displacement sensor and potentiometer control structure 600 mainly comprises a pen type local displacement sensor 601, a pen type local displacement sensor clamp 602, a trim bearing mounting groove 603, a low-friction spherical bearing 604, a single-ring low-friction potentiometer 605, a potentiometer limit groove 606, a T-shaped spring support 607, a spring 608 and a laser projection flat plate 609.
The pen-type local displacement sensor clamp 602 is I-shaped in side view, a fixing hole is formed in the pen-type local displacement sensor clamp 602 in the lateral direction on the center shaft and used for inserting the pen-type local displacement sensor 601, and an anchoring hole is vertically formed beside the fixing hole and used for locking the pen-type local displacement sensor 601; the center positions of the upper and lower end surfaces of the pen-type local displacement sensor clamp 602 are provided with through holes for placing bolts to fix the through holes in the grooves of the upper and lower end surfaces of the trim bearing mounting groove 603.
The trim bearing mounting groove 603 is of an I-shaped structure, the middle part of the trim bearing mounting groove is provided with a circular through hole with an edge fixing plate, the circular through hole is used for embedding the low-friction spherical bearing 604, one side of the through hole is provided with a square plate groove, two threaded holes are formed in the edge of the circular through hole along the axial direction of the circular through hole and used for fixing a square cover plate, and the upper end face and the lower end face of the trim bearing mounting groove are provided with grooves matched with the upper end face.
The low friction resistance spherical bearing 604 is assembled in the circular through hole at the center of the balancing bearing installation groove 603, the outer wall of the low friction resistance spherical bearing 604 and the inner wall of the circular through hole at the center of the balancing bearing installation groove 603 are consolidated by high-strength dry glue, the other side wall of the low friction resistance spherical bearing 604 is covered by a square cover plate and is anchored by bolts, the center part of the square cover plate is provided with a through hole with the same diameter as the through hole at the center of the balancing bearing installation groove 603, and the purpose is to connect the knob end of a single-ring low friction resistance potentiometer 605 with the inner wall of the low friction resistance spherical bearing 604.
The single-turn low-friction potentiometer 605 is the control pivot of the device, and the knob end is connected with the inner wall of the low-friction spherical bearing 604 and is consolidated by high-strength quick-drying glue. The terminal of the single-ring low-friction potentiometer 605 is arranged in the square groove of the potentiometer limit groove 606.
The potentiometer limiting groove 606 is a sector, the radian is 30 degrees, a square groove is arranged in the sector, the groove width is the same as the diameter of a single-ring low-friction potentiometer 605 wiring terminal, the groove depth is the same as the length of the single-ring low-friction potentiometer 605 wiring terminal, four centrosymmetric threaded holes are arranged on the bottom surface of the groove, and the through hole is used for anchoring the potentiometer limiting groove 606 at the central position of the lower end of the electric sliding table top 500. After the anchoring is completed, the single-ring low-friction potentiometer 605 is inserted into the square groove, and epoxy resin is filled in the hole for fixing. T-shaped spring supports 607 are arranged at the outer diameter edges of the potentiometer retaining grooves 606, and the central shafts of the T-shaped spring supports 607 are anchored at the outer diameter edges of the potentiometer retaining grooves 606 by bolts. The two wing ends of the T-shaped spring support 607 are sleeved with springs 608. The T-shaped spring support 607 and the spring 608 are installed so that the device can be quickly deformed or greatly deformed during the measurement process, so that the stability of the measurement device can be ensured, and the device is prevented from being out of control to cause equipment damage.
The laser projection flat 609 is a cuboid thin plate, is arranged above the local displacement sensor and potentiometer control structure 600 and is opposite to the laser displacement sensor 300, and a threaded hole is formed in the lower surface of the laser projection flat 609 for anchoring the laser projection flat on the upper surface of the trim bearing mounting groove 603; the upper surface of the laser projection plate 609 is smooth and flat for reflecting the laser projected by the laser displacement sensor 300.
The using process of the potentiometer control dynamic tracking bidirectional synchronous displacement measuring device comprises the following steps:
first, assembling the local displacement sensor and potentiometer control structure 600:
the low friction spherical bearing 604 is embedded into the trim bearing mounting groove 603, and the gap between the two is filled with high-strength dry glue for consolidation, and the other side wall of the low friction spherical bearing 604 is covered with a square cover plate and anchored by bolts, so that the outer ring of the low friction spherical bearing 604 can be fixed on the groove wall of the trim bearing mounting groove 603. The pen-type local displacement sensor clamp 602 is assembled perpendicular to the I-shaped trim bearing mounting groove 603, so that the upper end and the lower end of the pen-type local displacement sensor clamp 602 are fixed in grooves on the upper end face and the lower end face of the trim bearing mounting groove 603, the upper surface and the lower surface of the combination of the two are anchored, and then the upper surface of the combination is anchored with the laser projection plate 609. The pen-type local displacement sensor 601 is inserted into an outer side fixing hole on the center shaft of the pen-type local displacement sensor clamp 602, the position of the pen-type local displacement sensor clamp 602 is adjusted, and a bolt in the outer side anchoring hole is adjusted to lock the pen-type local displacement sensor 601. The knob end of the single-ring low-friction potentiometer 605 is rotated to the central position of the single ring, the knob end is inserted into the inner ring of the low-friction spherical bearing 604, and the high-strength quick-drying glue is infiltrated into the knob end to be fixedly connected with the inner wall of the inner ring of the low-friction spherical bearing 604. After the consolidation is completed, the single-ring low-friction potentiometer 605 main body is embedded into the potentiometer limiting groove 606, the T-shaped spring support 607 is arranged at the outer diameter edge of the potentiometer limiting groove 606, and the central shaft of the T-shaped spring support 607 is anchored at the outer diameter edge of the potentiometer limiting groove 606 by bolts. The two wing ends of the T-shaped spring support 607 are sleeved with springs 608. The potentiometer control structure 600 is obtained by completing the above steps.
Secondly, mounting a local displacement sensor and a potentiometer control structure 600 at the central position of the lower end of the electric sliding table 500; assembling a combined body formed by connecting the laser displacement sensor 300 with the separated rotatable fixture 400 through bolts at the center of the upper end of the electric sliding table top 500; after the components are combined, the combined body is connected with the electric sliding table 200, the central axis of the 500 long axis of the table top of the electric sliding table is parallel to the long axis of the electric sliding table 200, and the connecting shaft of the stepping motor 100 is connected with the head end of the transmission shaft of the electric sliding table 200; after the above components are assembled, the tail end of the electric sliding table 200 in the assembly is embedded into the electric sliding table base 700 and is leveled and fixed. In this step, all connections are anchored. And finishing the two steps, namely finishing the installation of the dynamic tracking bidirectional synchronous displacement measuring device controlled by a single potentiometer.
And thirdly, the assembled potentiometer control dynamic tracking bidirectional synchronous displacement measuring device is installed inside a pressure chamber of the triaxial apparatus, and the lower surface of the electric sliding table base 700 is in parallel contact with the upper surface of a lower disc of the pressure chamber of the triaxial apparatus.
And fourthly, adjusting the position of the potentiometer to control the dynamic tracking bidirectional synchronous displacement measuring device, so that a contact of the pen-type local displacement sensor 601 is in contact with a measuring point cushion block 900 adhered to the measuring point position on the surface of the triaxial sample, the contact point is the central position of the measuring point cushion block 900, the intersection of the extension line of the central line of the pen-type local displacement sensor 601 and the axial line of the triaxial sample 800 is ensured, the plane on the laser projection flat 609 is ensured to be vertical to the axial line of the sample, namely the laser projection flat 609 is in a horizontal state.
Fifthly, the split rotatable fixture 400 is adjusted so that the laser beam emitted by the laser displacement sensor 300 is perpendicular to the laser projection plate 609 and the plane formed by the incident laser ray and the reflected laser ray is parallel to the pen-type local displacement sensor 601, as shown in fig. 4. And (3) anchoring the potentiometer control dynamic tracking bidirectional synchronous displacement measuring device on the upper surface of the lower disc of the triaxial pressure chamber after the mounting position of the potentiometer control dynamic tracking bidirectional synchronous displacement measuring device is determined, and finishing the mounting of the potentiometer control dynamic tracking bidirectional synchronous displacement measuring device.
The installation number, the range selection and the like of the potentiometer control dynamic tracking bidirectional synchronous displacement measuring device are determined according to actual test requirements.
The invention has the beneficial effects that: the device can realize the accurate measurement of the axial-radial displacement of different local measuring points of the triaxial sample, can be used for static test and dynamic test, is not restricted by loading conditions, has simple equipment and does not need to modify the conventional triaxial; although the device belongs to contact measurement, only the contact of the local displacement sensor is finished with the surface of the triaxial sample, and the contact belongs to the point contact in the elastic range, so that the deformation in the triaxial sample test process cannot be interfered. The measuring device is simple in installation method, simple and convenient to operate and high in measuring precision, provides a more convenient and effective test means for the development of geotechnical tests and the research on the constitutive relation of the gravel materials, and has good popularization value.
Drawings
FIG. 1 is a perspective view of a potentiometer controlled dynamic tracking bi-directional synchronous displacement measurement device;
FIG. 2 is a front plan view of the potentiometer controlled dynamic tracking bi-directional synchronous displacement measuring device;
FIG. 3 is a side plan view of the potentiometer controlled dynamic tracking bi-directional synchronous displacement measuring device;
FIG. 4 is a top view of a potentiometer controlled dynamic tracking bi-directional synchronous displacement measurement device and a three-axis sample;
FIG. 5 is an exploded view of the components of the pen-based local displacement sensor and potentiometer control structure; FIG. 5(a) a pen-type partial displacement sensor 601; FIG. 5(b) a pen-type partial displacement sensor holder 602; FIG. 5(c) trim bearing mount groove 603; FIG. 5(d) a low friction spherical bearing 604; FIG. 5(e) a single turn low friction potentiometer 605; FIG. 5(f) is a combination of a potentiometer retaining slot 606, a T-shaped spring support 607 and a spring 608; FIG. 5(g) laser projection plate 609;
FIG. 6 is a schematic diagram of a potentiometer controlled dynamic tracking bidirectional synchronous displacement measuring device for measuring local deformation of a triaxial sample; FIG. 6(a) before deformation of the triaxial sample; FIG. 6(b) is a three-axis sample deformation; FIG. 6(c) after deformation of the triaxial sample;
FIG. 7 shows the result of measuring the local displacement of a three-axis sample by a potentiometer-controlled dynamic tracking bidirectional synchronous displacement measuring device; FIG. 7(a) axial displacement; FIG. 7(b) radial displacement; FIG. 7(c) shows the actual displacement of the measurement point;
FIG. 8 shows the approval parameters of the laser displacement sensor and the control parameters of the potentiometer during the measurement of the local part of the three-axis sample by the potentiometer-controlled dynamic tracking bidirectional synchronous displacement measuring device; FIG. 8(a) laser displacement sensor approval parameters; FIG. 8(b) potentiometer control parameters;
in the figure: 100 step motors; 200 electric sliding tables; 300 laser displacement sensor; 400 separate rotatable clamps; 500 electric sliding table top; 600 local displacement sensor and potentiometer control structure; 700 electric sliding table base; 800 triaxial sample; a measuring point cushion block 900;
601 pen type local displacement sensor; a 602 pen-type partial displacement sensor holder; 603 balancing the bearing mounting groove; 604 low friction spherical bearings; 605 single-turn low-friction potentiometer; 606 potentiometer limit slot; 607T-shaped spring support; 608 a spring; 609 laser projection plate;
300A measuring the laser displacement sensor in the initial state; 300B, a laser displacement sensor in the measuring process; 300C measuring the laser displacement sensor in the ending state; 500A, measuring the table top of the electric sliding table in the initial state; 500B, an electric sliding table top in the measurement process; 500C, measuring the table top of the electric sliding table in the finished state; 600A, measuring a local displacement sensor and a potentiometer control structure in an initial state; 600B local displacement sensor and potentiometer control structure in the measuring process; 600C measuring end state local displacement sensor and potentiometer control structure; 800A, measuring a triaxial sample in an initial state; 800B, measuring a three-axis sample in the process; 800C measures the finished state triaxial sample.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in detail and clearly in the following with reference to the accompanying drawings in the embodiments of the present invention. The described embodiments are merely illustrative of some, and not restrictive, of the many possible embodiments of the invention. In general, the components of the embodiments of the present invention illustrated in the drawings may be mounted and implemented in various positions or assemblies. All other embodiments, which can be derived by a person skilled in the art from the description of the specific embodiments of the invention without inventive step, are within the scope of protection of the invention.
In the following embodiments of the present invention, it should be noted that in the following drawings, some components have the same function, but do not belong to the same content at the same time, and different numbers are used, and in the text description, the components are distinguished by using the capital english alphabet a.b.c after the name, and in the specific implementation process, the components do not need to be distinguished, because the functions and the using method are completely the same.
In the embodiments of the present invention, it should be clearly understood that some terms indicating relative directions or relative positions, such as "upper end", "lower end", "front side", "back side", "central position", etc., are used to describe the orientation or positional relationship of a specific component with respect to other components. The description of the orientation or position is merely for convenience and clarity in describing the specific embodiment, and does not necessarily represent that the actual implementation engineering is strictly limited, and the orientation or position may be modified according to actual information such as the size of each component.
A potentiometer control dynamic tracking bidirectional synchronous displacement measuring device can dynamically track and synchronously measure local axial-radial displacement of a triaxial sample and is used for measuring the local axial-radial displacement of the sample in a conventional static and dynamic triaxial test.
As shown in fig. 1, fig. 2 and fig. 3, the potentiometer controlled dynamic tracking bidirectional synchronous displacement measuring device mainly comprises a stepping motor 100, an electric sliding table 200, a laser displacement sensor 300, a separated rotatable fixture 400, an electric sliding table top 500, a local displacement sensor and potentiometer control structure 600, and an electric sliding table base 700. The connecting shaft of the stepping motor 100 is connected with the head end of a transmission shaft of the electric sliding table 200; the laser displacement sensor 300 is connected with the separated rotatable fixture 400 through a bolt, and the stroke combination body of the laser displacement sensor and the separated rotatable fixture is assembled at the central position of the upper end of the electric sliding table top 500; a local displacement sensor and a potentiometer control structure 600 are assembled at the center of the lower end of the electric sliding table top 500; the lower end of the electric sliding table 200 is embedded into the electric sliding table base 700 and is leveled and fixed.
Referring to fig. 5(a), fig. 5(b), fig. 5(c), fig. 5(d), fig. 5(e), fig. 5(f) and fig. 5(g), the local displacement sensor and potentiometer control structure 600 mainly comprises a pen-type local displacement sensor 601, a pen-type local displacement sensor holder 602, a trim bearing mounting groove 603, a low-friction spherical bearing 604, a single-turn low-friction potentiometer 605, a potentiometer retaining groove 606, a T-shaped spring support 607, a spring 608 and a laser projection plate 609.
The pen-type local displacement sensor holder shown in fig. 5(b) has an i-shaped side view, a fixing hole of the pen-type local displacement sensor 601 is laterally arranged on the middle shaft, and an anchoring hole is vertically arranged beside the fixing hole for locking the pen-type local displacement sensor 601; the center positions of the upper and lower end surfaces are provided with through holes for placing bolts to fix the through holes in the grooves of the upper and lower end surfaces of the trim bearing mounting groove 603.
As shown in fig. 5(c), the trim bearing mounting groove 603 is an i-shaped structure, the middle portion is provided with a circular through hole with an edge fixing plate for embedding the low friction spherical bearing 604, one side of the through hole is provided with a square plate groove, two threaded holes are arranged at the edge of the circular through hole along the axial direction of the circular through hole for fixing a square cover plate, and the upper and lower end surfaces are provided with grooves matched with the upper and lower end surfaces of the pen-type local displacement sensor fixture 602.
The low friction spherical bearing 604 shown in FIG. 5(d) is assembled in the central circular through hole of the trim bearing mounting groove 603, the outer wall of the low friction spherical bearing 604 and the inner wall of the central circular through hole of the trim bearing mounting groove 603 are fixed by high-strength dry glue, and the other side wall of the low friction spherical bearing 604 is covered by a square cover plate with the same diameter as the through hole in the central circular through hole of the trim bearing mounting groove 603, and is anchored by bolts, and the purpose is to connect the knob end of the single-ring low friction potentiometer 605 with the inner wall of the low friction spherical bearing 604.
As shown in fig. 5(e), a single-turn low-friction potentiometer 605 is the control pivot of the device, and the end of the knob is connected to the inner wall of the low-friction spherical bearing 604 and fixed with high-strength quick-drying glue. The terminal of the single-ring low-friction potentiometer 605 is arranged in the square groove of the potentiometer limit groove 606.
The potentiometer limiting groove 606 shown in fig. 5(f) is a sector, the radian is 30 degrees, a square groove is arranged in the sector, the groove width is the same as the diameter of the terminal of the single-ring low-friction potentiometer 605, the groove depth is the same as the length of the terminal of the single-ring low-friction potentiometer 605, four centrosymmetric threaded holes are arranged on the bottom surface of the groove, and the through holes are used for anchoring the potentiometer limiting groove 606 at the central position of the lower end of the electric sliding table top 500. After the anchoring is completed, the single-ring low-friction potentiometer 605 is inserted into the square groove, and epoxy resin is filled in the hole for fixing. T-shaped spring supports 607 are arranged at the outer diameter edges of the potentiometer retaining grooves 606, and the central shafts of the T-shaped spring supports 607 are anchored at the outer diameter edges of the potentiometer retaining grooves 606 by bolts. The two wing ends of the T-shaped spring support 607 are sleeved with springs 608. The T-shaped spring support 607 and the spring 608 are installed so that the device can be quickly deformed or greatly deformed during the measurement process, so that the stability of the measurement device can be ensured, and the device is prevented from being out of control to cause equipment damage.
The laser projection plate 609 shown in fig. 5(g) is a rectangular thin plate, the upper surface of the laser projection plate is smooth and flat for reflecting laser projected by the laser displacement sensor 300, and the lower surface of the laser projection plate is provided with a threaded hole for anchoring the laser projection plate on the upper surface of the trim bearing mounting groove 603.
The potentiometer control dynamic tracking bidirectional synchronous displacement measuring device is used as follows:
firstly, assembling a local displacement sensor and a potentiometer control structure 600, embedding a low-friction spherical bearing 604 into a balancing bearing installation groove 603, pouring high-strength quick-drying glue into a gap between the low-friction spherical bearing and the balancing bearing installation groove for solidification, covering the other side wall of the low-friction spherical bearing 604 with a square cover plate, and anchoring the low-friction spherical bearing by using bolts, so that the outer ring of the low-friction spherical bearing 604 can be fixed on the groove wall of the balancing bearing installation groove 603. The pen-type local displacement sensor clamp 602 is assembled perpendicular to the I-shaped trim bearing mounting groove 603, so that the upper end and the lower end of the pen-type local displacement sensor clamp 602 are fixed in grooves on the upper end face and the lower end face of the trim bearing mounting groove 603, the upper surface and the lower surface of the combination of the two are anchored, and then the upper surface of the combination is anchored with the laser projection plate 609. The pen-type local displacement sensor 601 is inserted into an outer side fixing hole on the center shaft of the pen-type local displacement sensor clamp 602, the position of the pen-type local displacement sensor clamp 602 is adjusted, and a bolt in the outer side anchoring hole is adjusted to lock the pen-type local displacement sensor 601. The knob end of the single-ring low-friction potentiometer 605 is rotated to the central position of the single ring, the knob end is inserted into the inner ring of the low-friction spherical bearing 604, and the high-strength quick-drying glue is infiltrated into the knob end to be fixedly connected with the inner wall of the inner ring of the low-friction spherical bearing 604. After the consolidation is completed, the single-ring low-friction potentiometer 605 main body is embedded into the potentiometer limiting groove 606, the T-shaped spring support 607 is arranged at the outer diameter edge of the potentiometer limiting groove 606, and the central shaft of the T-shaped spring support 607 is anchored at the outer diameter edge of the potentiometer limiting groove 606 by bolts. The two wing ends of the T-shaped spring support 607 are sleeved with springs 608. The potentiometer control structure 600 is obtained by completing the above steps.
Secondly, mounting a local displacement sensor and a potentiometer control structure 600 at the central position of the lower end of the electric sliding table 500; assembling a combined body formed by connecting the laser displacement sensor 300 with the separated rotatable fixture 400 through bolts at the center of the upper end of the electric sliding table top 500; after the components are combined, the combined body is connected with the electric sliding table 200, the central axis of the 500 long axis of the table top of the electric sliding table is parallel to the long axis of the electric sliding table 200, and the connecting shaft of the stepping motor 100 is connected with the head end of the transmission shaft of the electric sliding table 200; after the above components are assembled, the tail end of the electric sliding table 200 in the assembly is embedded into the electric sliding table base 700 and is leveled and fixed. In this step, all connections are anchored. And finishing the two steps, namely finishing the installation of the dynamic tracking bidirectional synchronous displacement measuring device controlled by a single potentiometer.
And thirdly, the assembled potentiometer control dynamic tracking bidirectional synchronous displacement measuring device is installed inside a pressure chamber of the triaxial apparatus, and the lower surface of the electric sliding table base 700 is in parallel contact with the upper surface of a lower disc of the pressure chamber of the triaxial apparatus.
Fourthly, adjusting the position of a potentiometer control dynamic tracking bidirectional synchronous displacement measuring device to enable a contact of the pen-type local displacement sensor 601 to be in contact with a measuring point cushion block 900 adhered to a measuring point position on the surface of the triaxial sample, wherein the contact point is the central position of the measuring point cushion block 900, the intersection of the extension line of the central line of the pen-type local displacement sensor 601 and the axial line of the triaxial sample 800 is ensured, the plane on the laser projection flat 609 is ensured to be vertical to the axial line of the sample, namely the laser projection flat 609 is in a horizontal state;
fifthly, the split rotatable fixture 400 is adjusted so that the laser beam emitted by the laser displacement sensor 300 is perpendicular to the laser projection plate 609 and the plane formed by the incident laser ray and the reflected laser ray is parallel to the pen-type local displacement sensor 601, as shown in fig. 4. And (3) anchoring the potentiometer control dynamic tracking bidirectional synchronous displacement measuring device on the upper surface of the lower disc of the triaxial pressure chamber after the mounting position of the potentiometer control dynamic tracking bidirectional synchronous displacement measuring device is determined, and finishing the mounting of the potentiometer control dynamic tracking bidirectional synchronous displacement measuring device.
Furthermore, the installation number, the range selection and the like of the potentiometer control dynamic tracking bidirectional synchronous displacement measuring device are determined according to actual test requirements.
The measuring principle of a potentiometer-controlled dynamic tracking bidirectional synchronous displacement measuring device is as follows, and is described in detail according to the attached drawings 6(a), 6(b) and 6 (c):
referring to fig. 6(a), when the potentiometer controls the dynamic tracking bidirectional synchronous displacement measurement device to be installed, the triaxial sample 800A is in an initial state, and no displacement occurs at a local measurement point in any direction. The local displacement sensor and potentiometer control structure 600A remains perpendicular to the triaxial sample axis, at this time in a balanced position; the electric sliding table top 500A is in an initial state, and the corresponding axial displacement value is 0; the value of the laser displacement sensor 300A is at the measurement range equilibrium position, and the corresponding control reference displacement value is 0.
Referring to fig. 6(B), the triaxial apparatus starts to load, the triaxial sample 800B deforms, the local measurement point is displaced in both axial and radial directions, and the rotation in the plane of rotation of the local measurement point of the sample body is not considered; along with the displacement change of the local measuring point, the local displacement sensor and potentiometer control structure 600B rotates, the rotation central axis is a single-loop low-friction potentiometer 605, and the rotation angle value of the single-loop low-friction potentiometer 605 is recorded; the laser displacement sensor 300B measures that the distance between the laser displacement sensor and the laser projection panel 609 exceeds the balance position, and records the deviation value as a control reference displacement value; at this time, the electric sliding table 500B is not yet slid.
Referring to fig. 6(C), the triaxial apparatus continues to be loaded, and the deformation of the triaxial sample 800C is completed, which is a deformation point in the cyclic control and is not the deformation completion in the actual test process. The potentiometer controls a control program of a dynamic tracking bidirectional synchronous displacement measuring device to obtain a rotation angle numerical value of a single-ring low-friction potentiometer 605, a stepping motor 100 is controlled to push an electric sliding table 200, a table top 500C of the electric sliding table is displaced, when the rotation angle numerical value of the single-ring low-friction potentiometer 605 returns to a balance position, the stepping motor stops working, and at the moment, the displacement numerical value of the table top 500C of the electric sliding table is used as an axial displacement numerical value of a measuring point; meanwhile, the displacement value measured by the pen-type local displacement sensor is the radial displacement value of the measuring point. The value of the laser displacement sensor 300C at this time is recorded for checking whether the local displacement sensor and the potentiometer control structure 600C return to the equilibrium position.
The measurement process is repeated in the test process, and the control acquisition algorithm of the potentiometer control dynamic tracking bidirectional synchronous displacement measurement device is not detailed in the content of the invention.
Taking a gravel material consolidation drainage circulation loading and unloading test as an example, the method specifically explains how to accurately measure the local displacement of a triaxial sample by using the device disclosed by the invention, and further specifically explains the testing principle of the invention:
firstly, preparing a gravel triaxial sample according to geotechnical test regulation SL237-1999, and completing the installation of the gravel triaxial sample.
Further, the assembly of the potentiometer control dynamic tracking bidirectional synchronous displacement measuring device is completed according to the device assembly process, and is shown in the attached drawings 1, 2, 3, 4 and 5. And the assembled potentiometer control dynamic tracking bidirectional synchronous displacement measuring device is arranged in the pressure chamber of the triaxial apparatus. In this embodiment, only one potentiometer is needed to control the dynamic tracking bidirectional synchronous displacement measuring device.
Further, the gravel triaxial sample was aerated, saturated and consolidated in accordance with geotechnical test procedure SL 237-1999. Meanwhile, a control line of a stepping motor 100 of the potentiometer control dynamic tracking bidirectional synchronous displacement measuring device, a data line of a laser displacement sensor 300, a data line of a single-loop low-friction potentiometer 605 and a data line of a pen type local displacement sensor 601 are connected with an acquisition control card on a control acquisition electric control machine. All preparatory work before test loading was completed.
Further, a three-axis loading control program and a potentiometer control dynamic tracking bidirectional synchronous displacement measuring device control acquisition program are simultaneously activated, a test is started, data of a pen type local displacement sensor 601 are recorded, walking data of the electric sliding table 200 are recorded, data of the laser displacement sensor 300 are recorded, and data of a single-turn low-friction potentiometer 605 are recorded. Taking the walking data of the electric sliding table 200 as the axial displacement of a gravel material triaxial sample measuring point, as shown in fig. 7 (a); taking the data of the recording pen type local displacement sensor 601 as the radial displacement of the measuring point of the gravel material triaxial sample, as shown in fig. 7 (b); the actual deformation displacement of the three-axis test point of the gravel material is shown in FIG. 7 (c). The data of the single-loop low-friction potentiometer 605 is used as the control parameter of the measuring device, the device is adjusted in real time, effective tracking measurement is realized, and the data of the single-loop low-friction potentiometer 605 in the measuring process is shown in the attached figure 8 (a); the data of the laser displacement sensor 300 is used as the reference data of the control parameter of the measuring device for checking the control effectiveness, and the data of the laser displacement sensor 300 is shown in fig. 8 (b).
The above-mentioned embodiments only express the embodiments of the present invention, but not should be understood as the limitation of the scope of the invention patent, it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the concept of the present invention, and these all fall into the protection scope of the present invention.
Claims (3)
1. A potentiometer-controlled dynamic tracking bidirectional synchronous displacement measuring device is characterized in that the measuring device can dynamically track and synchronously measure local axial-radial displacement of a triaxial sample and comprises a stepping motor (100), an electric sliding table (200), a laser displacement sensor (300), a separated rotatable clamp (400), an electric sliding table top (500), a local displacement sensor and potentiometer control structure (600) and an electric sliding table base (700); the laser displacement sensor (300) and the separated rotatable fixture (400) are connected to form a combined body which is assembled at the upper end center position of one side surface of the electric sliding table top (500), the lower end center position of the side of the electric sliding table top (500) is assembled with a local displacement sensor and a potentiometer control structure (600), the other side surface of the electric sliding table top (500) is connected with the electric sliding table (200), and the long central axis of the electric sliding table top (500) is parallel to the long axial direction of the electric sliding table (200); the head end of a transmission shaft of the electric sliding table (200) is connected with a connecting shaft of the stepping motor (100), and the tail end of the electric sliding table (200) is embedded into the electric sliding table base (700) and is leveled and fixed;
the local displacement sensor and potentiometer control structure (600) comprises a pen type local displacement sensor (601), a pen type local displacement sensor clamp (602), a balancing bearing mounting groove (603), a low-friction spherical bearing (604), a single-ring low-friction potentiometer (605), a potentiometer limiting groove (606), a T-shaped spring support (607), a spring (608) and a laser projection flat plate (609);
the pen type local displacement sensor clamp (602) is of an I-shaped structure; a fixing hole of a pen type local displacement sensor (601) is laterally arranged on the middle shaft, and an anchoring hole is vertically arranged beside the fixing hole and used for locking the pen type local displacement sensor (601); a through hole is formed in the center of the upper end face and the lower end face and used for placing a bolt to enable the bolt to be fixed in grooves in the upper end face and the lower end face of a balancing bearing installation groove (603);
the trim bearing mounting groove (603) is of an I-shaped structure; a round through hole for embedding the low-friction spherical bearing (604) is formed in the middle of the balancing bearing mounting groove (603), a square plate groove is formed in one side of the through hole, and two threaded holes are formed in the edge of the round through hole along the axis direction of the round through hole and used for fixing a square cover plate; the upper end surface and the lower end surface of the balancing bearing mounting groove (603) are provided with grooves matched with the upper end surface and the lower end surface of a pen type local displacement sensor clamp (602);
the low-friction spherical bearing (604) is assembled in a central circular through hole of a balancing bearing installation groove (603), the side wall of the low-friction spherical bearing (604) is covered by a square cover plate and is anchored by a bolt, and the central part of the square cover plate is provided with a through hole with the same diameter as that of the central circular through hole of the balancing bearing installation groove (603), so that the knob end of a single-ring low-friction potentiometer (605) can be connected with the inner wall of the low-friction spherical bearing (604);
the single-ring low-friction potentiometer (605) is a control pivot, the knob end of the single-ring low-friction potentiometer is connected with the inner wall of the low-friction spherical bearing (604), epoxy resin is filled in a pore for consolidation, and the terminal of the single-ring low-friction potentiometer is placed in the square groove of the potentiometer limiting groove (606);
the potentiometer limiting groove (606) is a sector, a square groove is arranged in the sector, the groove width is the same as the diameter of a wiring terminal of the single-ring low-friction potentiometer (605), the groove depth is the same as the length of the wiring terminal of the single-ring low-friction potentiometer (605), a threaded hole is formed in the bottom surface of the groove, and the potentiometer limiting groove (606) is anchored at the central position of the lower end of the electric sliding table top (500); the outer diameter edge of the potentiometer limiting groove (606) is provided with a T-shaped spring support (607), the central shaft of the T-shaped spring support (607) is anchored at the outer diameter edge of the potentiometer limiting groove (606), and springs (608) are sleeved at two wing ends of the T-shaped spring support (607); the T-shaped spring support (607) and the spring (608) can ensure the stability of the measuring device in the measuring process;
the laser projection flat plate (609) is a cuboid thin plate, the upper surface of the laser projection flat plate is smooth and flat and is used for reflecting laser projected by the laser displacement sensor (300), and the lower surface of the laser projection flat plate is provided with a threaded hole for anchoring the laser projection flat plate on the upper surface of the balancing bearing mounting groove (603).
2. A potentiometer controlled dynamic tracking bidirectional synchronous displacement measuring device according to claim 1, wherein the outer wall of the low friction spherical bearing (604) and the inner wall of the central circular through hole of the trim bearing mounting groove (603) are consolidated by high-strength dry glue.
3. A potentiometer control dynamic tracking bidirectional synchronous displacement measuring device according to claim 1, wherein the arc of the sector of the potentiometer limit slot (606) is 30 °.
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| CN112798400A (en) * | 2021-01-22 | 2021-05-14 | 大连理工大学 | Device for omnibearing measurement of global deformation of sample by uniformly distributed laser displacement sensors |
| CN113959396A (en) * | 2021-10-08 | 2022-01-21 | 华能澜沧江水电股份有限公司 | Measuring device for local axial-radial deformation of hoop type triaxial sample and using method |
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